function init() {
  let htmlwidth = document.documentElement.clientWidth || document.body.clientWidth;
  let htmlDom = document.getElementsByTagName('html')[0];
  if(htmlwidth<1200) htmlDom.style.fontSize = htmlwidth / 7.5 + 'px';
  else htmlDom.style.fontSize = htmlwidth / 14 + 'px'

}
init();
window.addEventListener('resize', function () {
  init();
});